The highest of the Panch Kedar, Tungnath is 12,000ft or 3,670om above sea level. Ironically, it is also the easiest to reach, being just 4km from the roadhead, Chopta, a little cluster of untidy shacks surrounded by gorgeous meadows and deep deodar forests. The road crests here, dropping down to the Mandakini valley on one side, and the Alaknanda gorge on the other. From Gopeshwar (39km), a jeep-taxi should have you there in well under two hours.
Unless you are already acclimatized, though, I would suggest you don't rush up to the temple and back. Spend a couple of days acclimatizing in the wild meadows and forests around Chopta. And, if you have the time, extend your walk up to Chandrashila peak, which, at 4,130m, is a vantage eagles would vie for.
The 4km climb to Tungnath takes you north through a conifer forest. Then the switchbacks begin, the forest recedes, and you get an aerial view of the Chopta meadows. On both sides of the path, there are broad swathes of gassy slopes, with tiny clusters of wildflowers and berries. Halfway up, there are a couple of shacks where you can stop for a drink and a packet of biscuits. In less than three hours, you should reach a small kund, which signals that you have reached hallowed ground.
A few lodges just outside the temple offer basic accommodation, but if you want, the grasslands below the temple offer infinite camping possibilities.
If you want a chance at the views from Chandrashila, make an early departure from Tungnath, and climb as rapidly as your lungs allow. You have to backtrack down the stairs to the Chopta path, and skies open, the peak offers plenty of ledges to recline on, and deep, wide views of the Mandakini and Alaknanda valley and the white giants that water them.